CVE-2026-106491

Backstage is an open framework for building developer portals. Prior to 0.6.17, the @backstage/plugin-proxy-backend package is affected by improper input validation in proxy-backend. An authenticated Backstage user could craft a request URL that causes the proxy-backend to forward the request to a path outside the configured base path on the target server. This is limited to target servers already configured as proxy endpoints and requires Backstage authentication by default. This issue is fixed in version 0.6.17.

CVSS 3.1

6.4CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N

EPSS

0.3% chance of exploitation in the next 30 days; higher than 19% of CVEs (scores of 2026-10-25)

CWEs

CWE-20, CWE-22

Published

2026-10-06

Modified

2026-10-22

Record from

the NVD, synced 2026-10-22

Affected

• linuxfoundation:backstage
• linuxfoundation:backstage\/plugin-proxy-backend

Packages (OSV)

References

• https://github.com/backstage/backstage/commit/233287d0ce3133e41549bf92a7470c940a41753c
• https://github.com/backstage/backstage/releases/tag/v1.54.6
• https://github.com/backstage/backstage/security/advisories/GHSA-9ghw-48h5-v2w5

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